Abstract: AIM To study the relationship between rs1799983 polymorphism in endothelial nitric oxide synthase (eNOS) and susceptibility to hypertension and its interaction with obesity in Tujia population. METHODSGenotypes of 120 patients with hypertension and 140 control subjects were examined by polymerase chain reaction-based restriction fragment length polymorphism (PCR-RFLP). Unconditional logistic regression (ULR) was performed to assess hypertension risk and interaction with obesity. RESULTSA case-control analysis indicated that there was a higher risk of developing hypertension in CC/CT genotype carriers than in TT genotype carriers (OR=1.35, 95%CI: 1.22, 2.56, P=0.000; adjusted OR=1.61, 95%CI: 1.21, 3.01, P=0.000). By ULR method, obesity-positive subjects with genotype CT/CC had a hypertension risk 3.39 times higher than obesity-negative subjects with genotype TT (OR=3.39, 95%CI: 2.66, 5.36, P=0.000) (RERI=1.94, 95%CI: 1.41, 2.77; API=0.59, 95%CI: 0.33, 0.84; S=1.46, 95%CI: 1.37, 2.66). CONCLUSIONeNOS rs1799983 polymorphism is associated with increased risk for hypertension in Tujia population with a synergistic interaction.